diff --git a/src/anemoi/inference/plugin.py b/src/anemoi/inference/plugin.py
index 7aad9ec..1a47e01 100644
--- a/src/anemoi/inference/plugin.py
+++ b/src/anemoi/inference/plugin.py
@@ -93,7 +93,12 @@ def parse_model_args(self, args):
 
     @cached_property
     def runner(self):
-        return PluginRunner(self._checkpoint, device=self.device)
+        return PluginRunner(
+            self._checkpoint,
+            device=self.device,
+            pre_processors=self.pre_processors(),
+            post_processors=self.post_processors(),
+        )
 
     def run(self):
         if self.deterministic:
@@ -111,6 +116,14 @@ def run(self):
 
         output.close()
 
+    def pre_processors(self):
+        # To override in subclasses
+        return []
+
+    def post_processors(self):
+        # To override in subclasses
+        return []
+
     # Below are methods forwarded to the checkpoint
 
     @property
diff --git a/src/anemoi/inference/postprocess.py b/src/anemoi/inference/postprocess.py
deleted file mode 100644
index 7740cdf..0000000
--- a/src/anemoi/inference/postprocess.py
+++ /dev/null
@@ -1,42 +0,0 @@
-# (C) Copyright 2024 Anemoi contributors.
-#
-# This software is licensed under the terms of the Apache Licence Version 2.0
-# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
-#
-# In applying this licence, ECMWF does not waive the privileges and immunities
-# granted to it by virtue of its status as an intergovernmental organisation
-# nor does it submit to any jurisdiction.
-
-
-import logging
-
-import numpy as np
-
-LOG = logging.getLogger(__name__)
-
-
-class Noop:
-
-    def __call__(self, source):
-        yield from source
-
-
-class Accumulator:
-    """Accumulate fields from zero and return the accumulated fields"""
-
-    def __init__(self, accumulations):
-        self.accumulations = accumulations
-        LOG.info("Accumulating fields %s", self.accumulations)
-
-        self.accumulators = {}
-
-    def __call__(self, source):
-        for state in source:
-            for accumulation in self.accumulations:
-                if accumulation in state["fields"]:
-                    if accumulation not in self.accumulators:
-                        self.accumulators[accumulation] = np.zeros_like(state["fields"][accumulation])
-                    self.accumulators[accumulation] += np.maximum(0, state["fields"][accumulation])
-                    state["fields"][accumulation] = self.accumulators[accumulation]
-
-            yield state
diff --git a/src/anemoi/inference/runner.py b/src/anemoi/inference/runner.py
index 2856763..6a5f3d7 100644
--- a/src/anemoi/inference/runner.py
+++ b/src/anemoi/inference/runner.py
@@ -21,9 +21,9 @@
 
 from .checkpoint import Checkpoint
 from .context import Context
-from .postprocess import Accumulator
-from .postprocess import Noop
 from .precisions import PRECISIONS
+from .processors import Accumulator
+from .processors import Chain
 
 LOG = logging.getLogger(__name__)
 
@@ -63,6 +63,8 @@ def __init__(
         verbosity=0,
         inference_options=None,
         development_hacks={},  # For testing purposes, don't use in production
+        pre_processors=None,
+        post_processors=None,
     ):
         self._checkpoint = Checkpoint(checkpoint)
 
@@ -79,14 +81,15 @@ def __init__(
 
         # This could also be passed as an argument
 
-        self.postprocess = Noop()
+        self.preprocess = Chain("pre-processors", pre_processors)
+        self.postprocess = Chain("post-processors", post_processors)
 
         if accumulations is True:
             # Get accumulations from the checkpoint
             accumulations = self.checkpoint.accumulations
 
         if accumulations:
-            self.postprocess = Accumulator(accumulations)
+            self.postprocess.append(Accumulator(accumulations))
 
         self._input_kinds = {}
         self._input_tensor_by_name = []
@@ -108,6 +111,12 @@ def checkpoint(self):
 
     def run(self, *, input_state, lead_time):
 
+        # Shallow copy to avoid modifying the user's input state
+        input_state = input_state.copy()
+        input_state["fields"] = input_state["fields"].copy()
+
+        input_state = self.preprocess(input_state)
+
         self.constant_forcings_inputs = self.checkpoint.constant_forcings_inputs(self, input_state)
         self.dynamic_forcings_inputs = self.checkpoint.dynamic_forcings_inputs(self, input_state)
         self.boundary_forcings_inputs = self.checkpoint.boundary_forcings_inputs(self, input_state)
diff --git a/src/anemoi/inference/runners/plugin.py b/src/anemoi/inference/runners/plugin.py
index d218282..1a15dc6 100644
--- a/src/anemoi/inference/runners/plugin.py
+++ b/src/anemoi/inference/runners/plugin.py
@@ -21,8 +21,8 @@
 class PluginRunner(Runner):
     """A runner implementing the ai-models plugin API."""
 
-    def __init__(self, checkpoint: str, *, device: str):
-        super().__init__(checkpoint, device=device)
+    def __init__(self, checkpoint: str, *, device: str, pre_processors=None, post_processors=None):
+        super().__init__(checkpoint, device=device, pre_processors=pre_processors, post_processors=post_processors)
 
     # Compatibility with the ai_models API